barrier

Etymology

From Old French barriere (compare French barrière).

Pronunciation

• (UK) IPA^(key): /ˈbæɹi.ə(ɹ)/
• (US, Mary–marry–merry distinction) IPA^(key): /ˈbæɹi.əɹ/
• (US, Mary–marry–merry merger) IPA^(key): /ˈbɛɹi.əɹ/

• Audio (US)

  (file)

• Rhymes: -æɹiə(ɹ)

Noun

barrier (plural barriers)

1. A structure that bars passage.
2. An obstacle or impediment.
   • 2013 June 1, “Towards the end of poverty”, in The Economist‎, volume 407, number 8838, page 11:

     America’s poverty line is $63 a day for a family of four. In the richer parts of the emerging world $4 a day is the poverty barrier. But poverty’s scourge is fiercest below $1.25 ([…]): people below that level live lives that are poor, nasty, brutish and short.

3. A boundary or limit.
4. (grammar) A node (in government and binding theory) said to intervene between other nodes A and B if it is a potential governor for B, c-commands B, and does not c-command A.
5. (physiology) A separation between two areas of the body where specialized cells allow the entry of certain substances but prevent other substances to enter.